Forums

Which oscillator?

Started by Unknown October 17, 2014
On Saturday, October 18, 2014 3:02:25 PM UTC+1, Jan Panteltje wrote:
> On a sunny day (Sat, 18 Oct 2014 06:51:56 -0700 (PDT)) it happened > meow2222@care2.com wrote in > <2cfe163d-d52d-4766-9e27-b044a0a09435@googlegroups.com>: > >On Saturday, October 18, 2014 9:34:30 AM UTC+1, Jan Panteltje wrote: > >> On a sunny day (Fri, 17 Oct 2014 16:10:47 -0700 (PDT)) it happened > >> meow2222@care2.com wrote in > >> <4d0d5433-ef35-486a-9176-4123b679d440@googlegroups.com>:
> >> >Hi folks. I'm looking to choose a couple of oscillators for 3rd world=
construction/use, and I'm very rusty on the properties
> >> >of > >> >the numerous options. What's essential: > >> >- reasonably frequency stable with quite widely varying psu voltage, =
eg 5-9v
> >> >- discrete parts only, ICs can't be counted on to be available > >> >- common parts only, no tapped inductors etc > >> >- the minimum of parts is a major choice factor > >> > > >> >Plusses would be: > >> >no inductors > >> >npn trs only
> >> mm that last thing... > >> I got a lot of UJTs from ebay a while back. > >> Simpler is hard. > >> I showed a LED strobe with one here a while back.
> >The need for a UJT would much reduce the ability to build the things. A =
UJT LED strobe does sound interestingly minimal, but I'm
> >not convinced its practical due to the shortage of UJTs in scrap applian=
ces.
> Its probably cheaper to buy 100 UJTs on ebay than to get all that scrap, > look for usable NPNs, get those out.. etc. > I've build things from scrap PCBs, > these days maybe the resitors are marked, but the capacitiors wont be, > its all SMD, the transistors wont be marked either. > Now you need a C and ohm meter too. > Depends a bit how old the scrap is. > With modern SMD parts you can do cheaper with new, > all you need is a soldering iron and a pair of pliers. > Its not like an SMD resistor or capacitor is expensive. > Then better buy for 10$ parts, > and they can make a hundred of these things and get hands on feeling with=
SMD.
> Veroboard.
This is primarily for people stuck in poverty rather than established busin= esses. So fancy things like new parts, veroboard, electric irons etc are ou= t of the question. Electronic scrap is found by the roadside and at tips. S= oldering can be done with a nail, and a pointed screw works well for removi= ng through hole parts. For now I want to get as much bang for as little buck as possible, using ci= rcuits that can be made from the widest possible range of tron scrap. NT
On a sunny day (Sat, 18 Oct 2014 09:44:37 -0700 (PDT)) it happened
meow2222@care2.com wrote in
<787ceee8-6eba-4026-bbb0-77209baaccb0@googlegroups.com>:

>On Saturday, October 18, 2014 3:02:25 PM UTC+1, Jan Panteltje wrote: >> On a sunny day (Sat, 18 Oct 2014 06:51:56 -0700 (PDT)) it happened >> meow2222@care2.com wrote in >> <2cfe163d-d52d-4766-9e27-b044a0a09435@googlegroups.com>: >> >On Saturday, October 18, 2014 9:34:30 AM UTC+1, Jan Panteltje wrote: >> >> On a sunny day (Fri, 17 Oct 2014 16:10:47 -0700 (PDT)) it happened >> >> meow2222@care2.com wrote in >> >> <4d0d5433-ef35-486a-9176-4123b679d440@googlegroups.com>: > >> >> >Hi folks. I'm looking to choose a couple of oscillators for 3rd world= > construction/use, and I'm very rusty on the properties >> >> >of >> >> >the numerous options. What's essential: >> >> >- reasonably frequency stable with quite widely varying psu voltage, = >eg 5-9v >> >> >- discrete parts only, ICs can't be counted on to be available >> >> >- common parts only, no tapped inductors etc >> >> >- the minimum of parts is a major choice factor >> >> > >> >> >Plusses would be: >> >> >no inductors >> >> >npn trs only > >> >> mm that last thing... >> >> I got a lot of UJTs from ebay a while back. >> >> Simpler is hard. >> >> I showed a LED strobe with one here a while back. > >> >The need for a UJT would much reduce the ability to build the things. A = >UJT LED strobe does sound interestingly minimal, but I'm >> >not convinced its practical due to the shortage of UJTs in scrap applian= >ces. > >> Its probably cheaper to buy 100 UJTs on ebay than to get all that scrap, >> look for usable NPNs, get those out.. etc. >> I've build things from scrap PCBs, >> these days maybe the resitors are marked, but the capacitiors wont be, >> its all SMD, the transistors wont be marked either. >> Now you need a C and ohm meter too. >> Depends a bit how old the scrap is. >> With modern SMD parts you can do cheaper with new, >> all you need is a soldering iron and a pair of pliers. >> Its not like an SMD resistor or capacitor is expensive. >> Then better buy for 10$ parts, >> and they can make a hundred of these things and get hands on feeling with= > SMD. >> Veroboard. > >This is primarily for people stuck in poverty rather than established busin= >esses. So fancy things like new parts, veroboard, electric irons etc are ou= >t of the question. Electronic scrap is found by the roadside and at tips. S= >oldering can be done with a nail, and a pointed screw works well for removi= >ng through hole parts. > >For now I want to get as much bang for as little buck as possible, using ci= >rcuits that can be made from the widest possible range of tron scrap. > > >NT
I admire your good intentions, as a kid I have soldered with a screwdriver heated in the coal fireplace. Parts were a LOT bigger then, no transistors... The soldering was not reall reliable, no flux... :-) S39 flux (what plumbers use here) killed capacitors.. So somebody is going to go there and teach those kids or people how to do that. If it is you I would spend that same amount you spend on travel expenses on some electronics kits or ebay parts. Reality. They would have to know about that anyways if it is for their future. It would be a 'holding hand' lesson, with a million questions. I would donate the parts, that cost would be nothing compared to the cost of time and travel. If they can read they could use a good book on the subject as guide too.
On Sun, 19 Oct 2014 02:12:42 +1000, Tim Wescott <tim@seemywebsite.com>  
wrote:

> On Sat, 18 Oct 2014 06:10:29 -0700, meow2222 wrote: > >> On Saturday, October 18, 2014 2:30:27 AM UTC+1, Tim Wescott wrote: >>> On Fri, 17 Oct 2014 16:10:47 -0700, meow2222 wrote: >> >>> > Hi folks. I'm looking to choose a couple of oscillators for 3rd world >>> > construction/use, and I'm very rusty on the properties of the >>> > numerous options. What's essential: >>> > - reasonably frequency stable with quite widely varying psu voltage, >>> > eg 5-9v - discrete parts only, ICs can't be counted on to be >>> > available - common parts only, no tapped inductors etc - the minimum >>> > of parts is a major choice factor >>> > > Plusses would be: >>> > no inductors npn trs only >>> > > The prime app is as a sig-gen. Frequncy range etc are determined >>> > > more by >>> > BOM than anything else, its down to what can we manage with a few >>> > cheap parts. (I've used opamps for basic miniature pocket use sig >>> > gens, but can't do that here.) >>> > > A 2nd app for an LED strobe might also be handy. This would need a >>> > mark/space of 10:1 or so to get decent clarity of speed measurements. >>> > Again its a question of what can we do at minimum cost. >>> > > > thank you, NT >> >>> It's cool that you're working on this. >>> I'd suggest that if you're going to be doing much of this, that you >>> start collecting electronics and amateur radio magazines from the >>> 1960's and '70's. There should be a rich supply there. >> >> Interesting. >> >>> You can make a reasonably stable 6V-ish zener from a reverse-biased BE >>> junction on a 2N2222-ish transistor. Then use that as a reference for >>> a regulated supply. >> >> Does that trick work with almost any npn tr? Its impractical to specify >> specific trs, but no problem to say 'this size npn.' Zeners should be >> available too, but its potluck what the voltages would be. > > It works with all the small-signal ones that I've tried. I think it's a > direct consequence of the doping profiles you need to get good transistor > action -- but I don't know.
I've got a bunch of BC547B's (jelly bean type npn with gain of 400) and they all zener (rBE) at just shy of 9v - I was wondering if I should post about them and ask if anyone has seen similar and what might be the other consequences of using these strange beasts. Normally(?) a BC547 zeners at 5-6 volts.
In article <2cfe163d-d52d-4766-9e27-b044a0a09435@googlegroups.com>, 
meow2222@care2.com says...
> > mm that last thing... > > I got a lot of UJTs from ebay a while back. > > Simpler is hard. > > I showed a LED strobe with one here a while back. > > The need for a UJT would much reduce the ability to build the things. A UJT LED strobe does sound interestingly minimal, but I'm not convinced its practical due to the shortage of UJTs in scrap appliances. > > > NT > >
you can use sensitive gate SCR's and make oscillators, so it isn't a horrible deal if UJT become in short supply.. Jamie
On Saturday, October 18, 2014 5:12:42 PM UTC+1, Tim Wescott wrote:
> On Sat, 18 Oct 2014 06:10:29 -0700, meow2222 wrote: > > On Saturday, October 18, 2014 2:30:27 AM UTC+1, Tim Wescott wrote: > >> On Fri, 17 Oct 2014 16:10:47 -0700, meow2222 wrote:
> > >> You can make a reasonably stable 6V-ish zener from a reverse-biased BE > >> junction on a 2N2222-ish transistor. Then use that as a reference for > >> a regulated supply.
> > > Does that trick work with almost any npn tr? Its impractical to specify > > specific trs, but no problem to say 'this size npn.' Zeners should be > > available too, but its potluck what the voltages would be.
> It works with all the small-signal ones that I've tried. I think it's a > direct consequence of the doping profiles you need to get good transistor > action -- but I don't know. > I learned it from some ham radio electronics book or another.
Thanks, handy to know NT
On Saturday, October 18, 2014 5:12:42 PM UTC+1, Tim Wescott wrote:
> On Sat, 18 Oct 2014 06:10:29 -0700, meow2222 wrote: > > On Saturday, October 18, 2014 2:30:27 AM UTC+1, Tim Wescott wrote: > >> On Fri, 17 Oct 2014 16:10:47 -0700, meow2222 wrote:
> > Basically want a pocket tool thats useful to people learning and doing > > electronics in its various forms. So I guess there's room for minimal > > and more capable kit. I'm looking to start with something minimal as its > > quicker to design & write up, and quicker & cheaper to build, thus can > > benefit more people. So for the first version, pretty much any wave > > would be of use.
> I think that to start you want some sort of multivibrator, and you want > to pull in your horns on stability and accuracy.
I guess that's inevitably true. How can one have a fixed Vbe threshold plus variable Vcc, yet get consistent timing. I don't want to waste parts & battery power on a regulator stage.... unless I just zener regulate the feedback path? Multivibrator: 2 tr 2 C 2 D 4 R RCRC osc: 1 tr 3 C 4 R Looks like the latter wins, unless it runs into some problem down the line. I think its spice time. NT
On Saturday, October 18, 2014 6:26:02 PM UTC+1, David Eather wrote:
> On Sun, 19 Oct 2014 02:12:42 +1000, Tim Wescott <tim@seemywebsite.com> > wrote: > > On Sat, 18 Oct 2014 06:10:29 -0700, meow2222 wrote: > >> On Saturday, October 18, 2014 2:30:27 AM UTC+1, Tim Wescott wrote: > >>> On Fri, 17 Oct 2014 16:10:47 -0700, meow2222 wrote:
> >>> > Hi folks. I'm looking to choose a couple of oscillators for 3rd world > >>> > construction/use, and I'm very rusty on the properties of the > >>> > numerous options. What's essential: > >>> > - reasonably frequency stable with quite widely varying psu voltage, > >>> > eg 5-9v - discrete parts only, ICs can't be counted on to be > >>> > available - common parts only, no tapped inductors etc - the minimum > >>> > of parts is a major choice factor > >>> > > Plusses would be: > >>> > no inductors npn trs only > >>> > > The prime app is as a sig-gen. Frequncy range etc are determined > >>> > > more by > >>> > BOM than anything else, its down to what can we manage with a few > >>> > cheap parts. (I've used opamps for basic miniature pocket use sig > >>> > gens, but can't do that here.) > >>> > > A 2nd app for an LED strobe might also be handy. This would need a > >>> > mark/space of 10:1 or so to get decent clarity of speed measurements. > >>> > Again its a question of what can we do at minimum cost. > >>> > > > thank you, NT > >> > >>> It's cool that you're working on this. > >>> I'd suggest that if you're going to be doing much of this, that you > >>> start collecting electronics and amateur radio magazines from the > >>> 1960's and '70's. There should be a rich supply there. > >> > >> Interesting. > >> > >>> You can make a reasonably stable 6V-ish zener from a reverse-biased BE > >>> junction on a 2N2222-ish transistor. Then use that as a reference for > >>> a regulated supply. > >> > >> Does that trick work with almost any npn tr? Its impractical to specify > >> specific trs, but no problem to say 'this size npn.' Zeners should be > >> available too, but its potluck what the voltages would be. > > > > It works with all the small-signal ones that I've tried. I think it's a > > direct consequence of the doping profiles you need to get good transistor > > action -- but I don't know.
> I've got a bunch of BC547B's (jelly bean type npn with gain of 400) and > they all zener (rBE) at just shy of 9v - I was wondering if I should post > about them and ask if anyone has seen similar and what might be the other > consequences of using these strange beasts. Normally(?) a BC547 zeners at > 5-6 volts.
I assume they're marked BC547 because they meet all the specs, so should be fine for all the usual apps. Unless I'm mistaken, Veb spec is a min figure. Only if you rely on Veb breakdown are you into not-fully specified territory. NT
On Saturday, October 18, 2014 6:03:41 PM UTC+1, Jan Panteltje wrote:
> On a sunny day (Sat, 18 Oct 2014 09:44:37 -0700 (PDT)) it happened > meow2222@care2.com wrote in > <787ceee8-6eba-4026-bbb0-77209baaccb0@googlegroups.com>: > >> >> meow2222@care2.com wrote in > >> >> <4d0d5433-ef35-486a-9176-4123b679d440@googlegroups.com>:
> >> >> >Hi folks. I'm looking to choose a couple of oscillators for 3rd world= > > construction/use, and I'm very rusty on the properties > >> >> >of > >> >> >the numerous options. What's essential:
...
> >This is primarily for people stuck in poverty rather than established busin= > >esses. So fancy things like new parts, veroboard, electric irons etc are ou= > >t of the question. Electronic scrap is found by the roadside and at tips. S= > >oldering can be done with a nail, and a pointed screw works well for removi= > >ng through hole parts. > > > >For now I want to get as much bang for as little buck as possible, using ci= > >rcuits that can be made from the widest possible range of tron scrap.
> I admire your good intentions, > as a kid I have soldered with a screwdriver heated in the coal fireplace. > Parts were a LOT bigger then, no transistors... > The soldering was not reall reliable, no flux... > :-) > S39 flux (what plumbers use here) killed capacitors.. > So somebody is going to go there and teach those kids or people how to do that.
No. Once the circuit is worked out, it will go into a booklet that explains how to do it. Other booklets in the series will explain other aspects of things.
> If it is you I would spend that same amount you spend on travel expenses on some electronics kits > or ebay parts. > Reality. > They would have to know about that anyways if it is for their future. > It would be a 'holding hand' lesson, with a million questions. > I would donate the parts, that cost would be nothing compared to the cost of time and travel. > If they can read they could use a good book on the subject as guide too.
Books are the only real option when its to be accessible to over a billion people. I learnt electronics from books, for most of us there was no internet. These will also go online for people that can access it. There its practical to include a FAQ, links to related info etc. NT
On Saturday, October 18, 2014 12:10:47 AM UTC+1, meow...@care2.com wrote:

> Hi folks. I'm looking to choose a couple of oscillators for 3rd world con=
struction/use, and I'm very rusty on the properties of the numerous options= . What's essential:
> - reasonably frequency stable with quite widely varying psu voltage, eg 5=
-9v
> - discrete parts only, ICs can't be counted on to be available > - common parts only, no tapped inductors etc > - the minimum of parts is a major choice factor > Plusses would be: > no inductors > npn trs only > The prime app is as a sig-gen. Frequncy range etc are determined more by =
BOM than anything else, its down to what can we manage with a few cheap par= ts. (I've used opamps for basic miniature pocket use sig gens, but can't do= that here.)
> A 2nd app for an LED strobe might also be handy. This would need a mark/s=
pace of 10:1 or so to get decent clarity of speed measurements. Again its a= question of what can we do at minimum cost.
> thank you, NT
OK, I got spicy.... Version 4 SHEET 1 880 680 WIRE -400 -48 -480 -48 WIRE 128 -48 -400 -48 WIRE -480 -32 -480 -48 WIRE -400 -16 -400 -48 WIRE 128 -16 128 -48 WIRE -480 64 -480 48 WIRE -400 64 -400 48 WIRE 128 80 128 64 WIRE 128 80 -640 80 WIRE 208 80 128 80 WIRE 336 80 288 80 WIRE 416 80 400 80 WIRE 416 208 416 80 WIRE -640 240 -640 80 WIRE -512 240 -560 240 WIRE -448 240 -512 240 WIRE -304 240 -368 240 WIRE -256 240 -304 240 WIRE -128 240 -176 240 WIRE 64 240 -128 240 WIRE 128 256 128 80 WIRE -512 288 -512 240 WIRE -304 288 -304 240 WIRE -128 288 -128 240 WIRE 64 304 64 240 WIRE -512 400 -512 352 WIRE -304 400 -304 352 WIRE -304 400 -512 400 WIRE -128 400 -128 352 WIRE -128 400 -304 400 WIRE -48 400 -128 400 WIRE 128 400 128 352 WIRE 128 400 -48 400 WIRE 416 400 416 288 WIRE 416 400 128 400 WIRE -48 432 -48 400 FLAG -480 64 0 FLAG -48 432 0 FLAG -400 64 0 SYMBOL npn 64 256 R0 SYMATTR InstName Q1 SYMATTR Value 2N2222 SYMBOL voltage -480 -48 R0 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V1 SYMATTR Value 5 SYMBOL res 112 -32 R0 SYMATTR InstName R4 SYMATTR Value 330 SYMBOL cap -416 -16 R0 SYMATTR InstName C1 SYMATTR Value 1000=B5 SYMBOL res -160 224 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R2 SYMATTR Value 1k SYMBOL res -352 224 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R1 SYMATTR Value 1k SYMBOL cap -320 288 R0 SYMATTR InstName C2 SYMATTR Value 0.47=B5 SYMBOL cap -144 288 R0 SYMATTR InstName C3 SYMATTR Value 0.47=B5 SYMBOL cap -528 288 R0 SYMATTR InstName C4 SYMATTR Value 0.47=B5 SYMBOL res -544 224 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R5 SYMATTR Value 1k SYMBOL res 304 64 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName Rout SYMATTR Value 10k SYMBOL cap 400 64 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName Cout SYMATTR Value 1=B5 SYMBOL res 400 192 R0 SYMATTR InstName Rload SYMATTR Value 1 TEXT -512 -88 Left 2 !.tran 0 1 0 10u startup But its suffering problems, and I'm not seeing why. The quiescent point & a= mplitude are rather low, and no tweak of R values seems to fix either - in = fact most such tweaks result in oscillation failing entirely. Ditto raising= Vcc. Drop Rout to 1k and it fails to oscillate. I'm missing something here= ... what? Haven't added battery R yet, will do that later. Just want to get a key iss= ue fixed first. NT
meow2222@care2.com wrote:
> Hi folks. I'm looking to choose a couple of oscillators for 3rd world construction/use, and I'm very rusty on the properties of the numerous options. What's essential: > - reasonably frequency stable with quite widely varying psu voltage, eg 5-9v > - discrete parts only, ICs can't be counted on to be available > - common parts only, no tapped inductors etc > - the minimum of parts is a major choice factor > > Plusses would be: > no inductors > npn trs only > > The prime app is as a sig-gen. Frequncy range etc are determined more by BOM than anything else, its down to what can we manage with a few cheap parts. (I've used opamps for basic miniature pocket use sig gens, but can't do that here.) > > A 2nd app for an LED strobe might also be handy. This would need a mark/space of 10:1 or so to get decent clarity of speed measurements. Again its a question of what can we do at minimum cost. > > > thank you, NT
Phase retard oscillator: R, C, Q; collector waveform tends to be square wave, and base waveform tends to be sine (at reduced amplitude). Been ages, think min gain for oscillation is 29.